The orator Callistratus was to plead in the cause which the city of Oropus had depending; and the expectation of the public was greatly raised, both by the powers of the orator, which were then in the highest repute, and by the importance of the trial. Demosthenes, hearing the governors and tutors agree among themselves to attend the trial, with much importunity prevailed on his master to take him to hear the pleadings. The master, having some acquaintance with the officers who opened the court, got his young pupil a seat where he could hear the orators without being seen. Callistratus had great success, and his abilities were extremely admired. Demosthenes was fired with a spirit of emulation. When he saw with what distinction the orator was conducted home, and complimented by the people, he was struck still more with the power of that commanding eloquence which could carry all before it. From this time, therefore, he bade adieu to the other studies and exercises in which boys are engaged, and applied himself with great assiduity to declaiming, in hopes of being one day numbered among the orators. Isaeus was the man he made use of as his preceptor in eloquence, though Isocrates then taught it; whether it was that the loss of his father incapacitated him to pay the sum of ten _minae_, which was that rhetorician's usual price, or whether he preferred the keen and subtle manner of Isaeus as more fit for public use. Hermippus says he met with an account in certain anonymous memoirs that Demosthenes likewise studied under Plato, and received great assistance from him in preparing to speak in public. He adds, that Ctesibius used to say that Demosthenes was privately supplied by Callias the Syracusan and some others, with the systems of rhetoric taught by Isocrates and Alcidamus, and made his advantage of them.